The present invention is directed to the field of orthopedic surgery. In particular, the present invention is directed to a new method for fracture reduction.
The currently available methods of fracture reduction are:                Casts/Braces        Plates:                    Conventional            Locking                        External Fixation        Intramedullary Nails        
Intramedullary nails have several advantages over other forms of fixation:                They are less invasive than plates;        They have a lower infection rate;        Nails are stronger than plates;        Nails have a mechanical advantage compared to plates;        The screws used with nails are more resistant to breakage due to the decreased moment arm;        Nails have a high rate of union;        Nails allow for anatomic alignment;        Casts/braces immobilize the limb and do not allow early motion; and        External fixators have a risk of pin tract infections.        
One of the currently available methods of interlocking IM Nails is to solely use screws, which can result in loss of reduction because of the inherent play in the screw-nail interface. A second method of interlocking IM Nails is to cap the screw at the contra lateral cortex, which increases fixation in the cortical bone. However, this method does not help the screw-nail interface. Additionally, pressure applied by the capping on one end may cause the distal end to move out of position. A third available method of interlocking IM Nails is to have the hole of the IM Nail lined with rubber to provide a more grippable material for the screws. However the inherent play in rubber does not provide sufficient locking. The rubber-lined IM Nails also suffer from the disadvantage of the possibility for foreign body reactions if flaking of the rubber occurs.
The method of the present invention, with a threaded guidewire in between the screws, locks the screw in place, eliminates play, and results in a more stable form of fixation of a fracture.
Two other patented methods of interlocking IM Nails were found, however, neither are currently marketed:                An interlocking Intramedullary Nail (U.S. Pat. No. 6,524,314, granted Feb. 25, 2003) provides for a different mechanism, using 2 lag screws and a locking screw. This product is currently not marketed but would be a difficult mechanism because there are only a couple of safe zones where the screws can be placed. With the addition of two screws placed for fixation, it may be difficult to find safe zones. Additionally, the screws may cross thread early prohibiting further insertion.        An interlocking Intramedullary Nail (U.S. Pat. No. 6,019,761, granted Feb. 1, 2000) provides for interlocking by placing a guidewire through one screw hole up to and out of the next. This patent also relies on drilling holes versus already manufactured holes and dropping wires through the holes and using the screws to cause the wires to interlock to the screws. This patent has a completely different means by which the interlocking would occur and be enhanced.        
This new mechanism, with the headless screw and outer screw, locks the screw in place to eliminate this play and result in a more stable form of fixation. A sleeve on the outer end of the screw will aid in the centering of the screw. Additionally, the option of placing an outer screw on both sides of the IM Nail offers a possibly stronger fixation with increased ability to center the IM Nail.